1. Field of the Invention
The present invention relates to a mobile communication terminal, and more particularly, to an antenna sharing apparatus for a mobile communication terminal which performs a radio frequency identification (RFID) function, and a method thereof.
2. Description of the Background Art
Some conventional mobile communication terminals are provided with enhanced communication functions, such as a wireless Internet function, a video on demand (VOD) function, a text and/or multimedia messaging function, or a wireless online game function. Some conventional mobile communication terminals are also provided with supplemental, non-communication functions, such as a camera function, a memo writing function, a schedule managing function, a bell sound function, or a wake-up call function.
Radio frequency identification (RFID) is an identification method which can be used to identify objects, such as, but not limited to products, animals, or human beings. RFID operates by integrating an electromagnetic or electrostatic coupling into a wireless frequency of an electrostatic spectrum. An advantage of RFID is that a direct contact with an RFID system or a scanning on a visible bandwidth is not required. An RFID system is typically composed of an antenna, a transceiver (also referred to as reader) and a tag (also referred to as a transponder). The antenna is connected to the transponder, which is activated when the antenna receives a radio frequency electric wave.
When the transponder is activated, it transmits data to the reader through the antenna. The reader may be connected to a controller, such as a programmable logic controller (PLC), used for various applications. For example, the controller may be used to track the entry of objects through a door, or update sales information in a database.
RFID may operate using low frequencies or high frequencies. Low frequencies (approximately 30 KHz-500 KHz) are typically used when communicating across short distances, at approximately 1.8 m or less. High frequencies (approximately 850 MHz-950 MHz or 2.4 GHz-2.5 GHz) are typically used when communicating across longer distances.
An RFID reader can be integrated, or attached to, a mobile communication terminal. If the RFID reader utilizes a frequency close to a frequency used by the mobile communication terminal for other communications, the RFID reader can share an antenna with the transceiver the mobile communication terminal uses for other communications. For example, a code division multiple access (CDMA) communication scheme is utilized in Korea for mobile communications, if an RFID reader operating on a frequency of approximately 900 MHz is integrated with a mobile communication terminal, a single antenna can be shared between the mobile communication terminal's CDMA transceiver and the RFID reader.
However, sharing an antenna between the CDMA transceiver and the RFID reader presents a problem, in that both cannot use the antenna simultaneously. Providing two separate antennas is not an optimum solution, since a minimum distance must be provided between the antennas to prevent signal interference, which necessarily increases the size of the mobile communication terminal.